This invention relates in general to support mechanisms, such as seats or beds, upon which some or all of a human body can be comfortably supported. More specifically, this invention relates to an improved structure for a variable support mechanism including a plurality of pneumatic bladders and an electronic control system for controlling the inflation and deflation of such bladders so as to comfortably support the body of a person on a support surface.
Generally speaking, a support mechanism is a device that includes a support surface adapted to engage and provide support for some or all of a human body. In a fixed support mechanism, the support surface is generally fixed in size and shape, deforming only as a result of forces being applied thereto. A wide variety of fixed support mechanisms are known in the art, including conventional seats and beds. However, a number of other fixed support mechanisms having support surfaces are known in the art, such as bandages, braces, and the like. It is known that when a portion of a human body contacts a support surface for an extended period of time, several undesirable effects can occur. These undesirable effects can range from minor muscle aches and fatigue to more severe discomforts. In the past, the solution to this problem involved human intervention to vary the position of the body of the person relative to the support surface.
More recently, a variety of support mechanisms have been developed having support surfaces that can be varied in shape or size provide an increased level of comfort to the person supported thereon. Such variable support mechanisms are commonly found, for example, in vehicular seat assemblies. In such vehicular seat assemblies, it is known to provide a plurality of pneumatic bladders at predetermined locations so as to individually support the thigh, ischial, and lumbar regions of the user. The variable support mechanism in such a vehicular seat assembly further includes a pump and one or more valves for selectively increasing or decreasing the amount of air contained within each or all of the bladders. By selectively inflating and deflating these bladders, the shape and size of the support surface can be quickly and easily customized in accordance with the body shape of the user. Such a device has been found to significantly increase the overall comfort to the user.
In the past, inflation and deflation of the bladders were performed manually by the user. Typically, this was accomplished by providing one or more electrical switches that controlled the operations of the pump and the valves. By properly manipulating the switches, the user could cause the bladders to be inflated and deflated as desired. Although these systems were effective, they were reliant upon manual manipulation and control by the user to effect adjustments. More recently, electronic control systems have been incorporated into these variable support mechanisms to permit the inflation and deflation of the bladders to occur automatically in response to predetermined sensed conditions. However, the cost and complexity of known variable support mechanisms and their associated electronic control systems have been found to be relatively high. Thus, it would be desirable to provide an improved structure for a variable support mechanism including a plurality of pneumatic bladders and an electronic control system for controlling the inflation and deflation of such bladders so as to comfortably support the body of a person on a support surface.
This invention relates to an improved structure for a variable support mechanism including a plurality of pneumatic bladders and an electronic control system for controlling the inflation and deflation of such bladders so as to comfortably support the body of a person on a support surface. Each of the bladders communicates through a solenoid operated valve with a common manifold. The operations of the solenoid operated valves are individually controlled by a microprocessor. A pressure sensor communicates with the manifold and generates electrical signals that is representative of the magnitude of the fluid pressure in the manifold to the microprocessor. The microprocessor is also connected to a solenoid operated vent valve that provides selective fluid communication between the manifold and the atmosphere. The microprocessor is further connected to a solenoid operated pressure valve that provides selective fluid communication between the manifold and a pump. An algorithm for controlling the operation of the electronic control system begins with an initial routine wherein the magnitude of the pressure in each of the bladders is sampled, measured, and stored by the electronic control system. Then, the algorithm enters a second routine wherein the measured pressure readings from the bladders are compared with respective target values and, in response to that comparison, are designated as being either (1) Too Low, (2) Too High, or (3) Within Limits. In a third routine of the algorithm, the bladders that have been identified as being Too Low are inflated until they have achieved their respective target values. Similarly, in a fourth routine of the algorithm, the bladders that have been identified as being Too High are deflated until they have achieved their respective target values. In a fifth routine of the algorithm, the electronic control system is placed an inactive mode, wherein no action occurs for a predetermined length of time. When the predetermined length of time expires, the algorithm enters a sixth routine wherein it is determined whether a sufficient period of time has elapsed to perform a user attention feature. If so, the algorithm enters a seventh routine wherein the pressure in one or more of the bladders is changed so as to generate a tactile indication to the user that the electronic control system is active and functioning. Then, the algorithm branches back to the first routine discussed above, wherein this cycle is repeated.
Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.